Alkaline phosphatase (APase) is expressed developmentally after stage II of sporulation in Bacillus subtilis. At this stage of sporulation there are two cell types, the mother cell and the forespore. It is of interest to determine which cell type is expressing the sporulation alkaline phosphatase in order to assess if APase expression occurs in the mother cell, the hypothesized functional location of the RNA polymerase sigma factor believed to direct transcription of APase.